Catheters are useful in performing a wide range of medical procedures, such as diagnostic heart catheterization, percutaneous transluminal coronary angioplasty, and various endocardial mapping and ablation procedures. It is often difficult, however, to selectively catheterize certain vessels of the human body due to the tortuous paths that the vessels follow. FIG. 1, for example, is a conceptual diagram useful in depicting the human aortic arch 100. As shown, the ascending aorta 110 rises from its origin at the aortic valve (not shown). The right common carotid 104 and the right subclavian 103 branch off of the brachiocephalic artery 102. The left common carotid 105 and the left subclavian artery 106 branch and rise from the aorta just before it turns and descends to the descending aorta 120. Dashed line 170 depicts a typical catheter placement that might be desirable in this context.
Normal aortic arches such as that shown in FIG. 1 rarely require intervention. Instead, interventionalists most often find themselves viewing and navigating diseased and abnormal aortic pathology, such as that shown in FIGS. 2A-2D, which depict assorted variant conditions of the human aortic arch (201-204). It is clear that navigation from the descending aorta 120, up over the arch, and then back to gain access to the right brachiocepalic artery 102 can be extremely difficult in such cases, particularly when the arteries are partially occluded with easily displaced and dislodged build-ups of plaque.
As a result, catheterization procedures often require multiple catheter exchanges—i.e., successively exchanging catheters with different sizes and/or stiffness to “build a rail” through which subsequent catheters can be inserted, eventually resulting in a wire and guide stiff enough to allow delivery of the intended interventional device (e.g., a stent, stent-graft, or the like).
Flexibility is therefore desirable in a catheter to allow it to track over a relatively flexible guidewire without causing the guidewire to pull out. That is, the “navigatibility” of the catheter is important. At the same time, the stiffness or rigidity of the same catheter is desirable to allow the guiding catheter to be robust enough to allow a relatively stiff device (such as a stent) to be tracked through the guiding catheter without causing the guiding catheter to lose position (i.e., becoming “dislodged”). If dislodgement occurs, the entire procedure of guide wire and guide catheter exchanges must be performed again from the beginning.
Often, an optimal balance is sought, such that the distal end of the catheter is flexible, and the proximal end is stiff to enable tracking. However, in order to move the stiff part of a catheter in place, the flexible section typically needs to be buried deep within the anatomy to get “purchase” and to hold position. In many instances, the anatomy does not allow for deep purchase. Accordingly, there is a need for catheter designs and methods that overcome these and other shortcomings of the prior art.